Relationship of energy dissipation efficiency to microstructural evolution in hot working of AISI 304 steel

On the basis of dynamic materials, modeling maps of energy dissipation efficiency were evaluated for 304 stainless steel from synthesized stress-strain curves over the ranges 900–1200 °C and 10−3 to 102 s−1. The constitutive equations as well as the ductility and microstructural evaluation were determined from torsion tests; these results were found to be in good agreement with the literature. High values of dissipation efficiency are obtained in association with the occurrence of flow curve peaks and flow softening resulting from dynamic recrystallization. However, the efficiency associated with the same softening mechanism during steady state at high strains is fairly low. In consequence, it seems an inadequate parameter to define the mechanism or to predict the ductility.